The hand squeeze tool of the present invention is of the same general type disclosed in U.S. Pat. No. 4,524,650 which issued June 25, 1985 in the name of the present inventor.
The squeeze tool described in the Patent, like the squeeze tool of the present invention, serves to convert squeezing motion into rotary motion on a variable torque basis, and serves to transmit the rotary motion to a screw, bolt, or other fastener, which is being tightened or loosened. The tool described in the Patent incorporates a pull lever and a varying force transmitting lever which operate in conjunction with a squeeze handle to provide a traveling fulcrum, so that when the squeeze handle is squeezed maximum torque and minimum speed are generated at the beginning of the stroke, and maximum speed and minimum torque are realized for the remainder of the stroke.
As described in the Patent, the principal objective of the squeeze tool is to overcome limitations inherent in prior art tools, such as ratchet wrenches. These limitations occur because the prior art ratchet wrenches exert a uniform torque on the bolt being turned, and, accordingly, when such a ratchet wrench is designed to exert sufficient torque initially to loosen a bolt, that torque continues when the bolt is being loosened and when it is not needed. This means that the prior art ratchet wrenches must be designed to incorporate more handle motion than is actually required for a particular operation, this is especially troublesome when space and/or accessibility are limited. Unlike the prior art ratchet wrench, the tool described in the Patent, as well as the tool of the present invention, automatically match the available torque with the torque required for a particular operation, and this is achieved by varying the torque. The net result is that a particular operation may be performed with maximum speed and yet with a generation of the required torque.
The tool of the present invention, like the tool described in the Patent, is intended to provide a capability which has been unavailable with the prior art manual, spiral ratchet, or motorized drivers, as mentioned briefly above. Manual drivers provide accurate control of a driving operation, but they are limited in speed to that at which the operator can rotate the tool. In addition, the wrist twisting motion required by a manual driver can become unnecessarily tiresome when used for light to medium duty applications. Spiral ratchet drivers provide poor control over the axial force applied to a driven element, since the turning torque is entirely dependent upon this axial force. As a result, spiral ratchet drivers are especially limited in their ability to remove threaded fasteners, and have limited power when the operator cannot place his body directly behind the axis of the force application.
Motorized drivers provide poor control of the rotation speed and torque applied to the driven element. The operator controls a switch, which in turn controls a motor, which finally powers the driven element. The user, accordingly, has little direct control over the events occurring at the driven element. In many instances, this lack of "feel" by the operator causes damage to the driven element and/or to its surroundings, especially in medium and light duty applications. The addition of a torque-limiting clutch in such a motorized tool is only a partial solution to the problem since it cannot account for the variables encountered in nonproduction type operations. Finally, the motorized tool is confined during use or storage by the need to be attached to a power supply line or battery charger.
Unlike the prior art tools described in the preceding paragraphs, the driver tool described in the Patent and the driver tool of the present invention allow for relatively high speed driving, while the operator maintains direct control over the axial force, torque, and turning rate applied to the driven element. The operator's hand is limited both in ultimate squeezing force and total possible squeezing motion. Therefore, to use the power created in the squeeze of the hand efficiently, the mechanism of the tool described in the Patent, and the tool of the present invention, allow the operator to amplify either his squeezing force or his squeezing motion. Through the action of further components within the driver, this variable force amplification is translated into a variable torque upon an output shaft. In this manner, the tool described in the Patent and the tool of the invention can accommodate a wide range of different driving conditions, constrained only by the total power available through the operator's hand.
A unique feature of the hand-powered variable torque drive tool of the present invention is that it provides two distinct operating zones as the operating handle is squeezed, so that during the initial portion of the squeeze stroke the torque generated by the drive shaft is a maximum and the rotational velocity of the drive shaft is a minimum, whereas during the latter part of the squeeze stroke the torque is a minimum and the velocity is a maximum. This enables the operator intuitively to take advantage of the variable torque feature of the invention, since the provision of a high torque region and a low torque region allows the operator to anticipate what torque magnification will occur as the control handle is squeezed. This is advantageous over a continuously varying torque where the torque capability of the tool as the operating handle is squeezed is less predictable.
The tool of the invention may be used to remove or install threaded fasteners, such as screws. It finds particular utility when a fastener requires light-to-medium turning torques for the major part of its travel in and out of a receiving hole, with maximum torque requirements occurring only during the initial loosening or final tightening of the fastener. The operator uses the high torque zone of the squeeze stroke only for initial loosening or final tightening of the fastener; and the rest of the driving operation is accomplished using the low torque high speed zone of the squeeze stroke, where a minimum of hand motion is required. Through use of the tool of the invention the foregoing operations become intuitive.
The tool of the present invention is also simpler and less complex than the tool described in the Patent, it may be manufactured more efficiently and on a more economical basis, and it includes innovations which make it more functional.
The tool of the invention is constructed for convenient and comfortable one-handed operation through the shape and contour of its handles. It may be used as a conventional ratchet driver in which the operator rotates the entire body of the tool back and forth about its driving axis to produce a net rotation of the driving tip, and when used in this manner, prolonged high torque driving may be accomplished.
When using the tool of the invention, the operator's hands are not in the region of the driving axis as they must be when using a conventional screwdriver, and fasteners may therefore be driven in corners, where the driving axis often closely parallels a wall or other obstruction, when the tool of the invention is used.
Standard one-fourth inch hexagonal shaft driver bits may be used with the tool of the invention, providing the largest possible variety of available bits and accessories. Because the tool requires no motor or batteries, it is light weight, which facilitates its use and storage.
The tool of the invention finds utility in various applications, including the removal and installation of panels and fixtures in automobiles, electronic and telecommunication apparatus, aircraft, spacecraft, industrial equipment, cabinets and doors. Moreover, the tool of the invention may conveniently be used in the disassembly or re-assembly of furniture, in the installation of plumbing hose clamps, and for general household use.
It is, accordingly, an objective of the present invention to provide an improved hand-squeeze driver tool for use with screw-type fasteners, and which exhibits a first distinct high torque, low speed zone as its operating handle is squeezed, for precise control and for tightening or loosening the fastener; followed by a second distinct low torque, high speed zone for driving the fastener. Selection of the zones is performed intuitively and instantaneously, requiring only that the operator squeeze the operating handle between the appropriate positions.
The driver tool of the invention provides an intimate control of the driving operations, since it is hand powered rather than motor powered, and this minimizes the occurrence of damage to fasteners and/or assemblies in which they are used. The tool of the invention is entirely portable, both in use and in storage, since it requires no power supply line or batteries. The tool is particularly advantageous, as mentioned above, in that it may be inexpensively produced by conventional mass production means. Moreover, it has a pleasing overall configuration and appearance.